fix: httpx.ParseJsonBody error when request has []byte field #4450

[studyzy]

--bug=4450

[kevwan]

How can we know it's base64 encoded?

[studyzy]

How can we know it's base64 encoded?

Since golang official json.Marshal/json.Unmarshal use base64 encoding to process []byte.

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 94.51%. Comparing base (8690859) to head (6394a2d).
Report is 227 commits behind head on master.

Files with missing lines	Patch %	Lines
core/mapping/unmarshaler.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
core/mapping/unmarshaler.go	95.08% <57.14%> (-1.40%)	⬇️

... and 7 files with indirect coverage changes